The Great Plains, a vast region spanning the central United States and parts of Canada east of the Rocky Mountains, is characterized by prairies, steppes, and grasslands. Its climate varies from semi-arid in the west to humid continental and subtropical in the east. Drought, a recurring natural phenomenon, leads to serious hydrologic imbalance in this area. Understanding drought dynamics in the Great Plains is important due to its influence on the region’s environment, economy, and communities.
Understanding Past Droughts
The Great Plains has a long history of drought, with tree-ring records indicating periods lasting for decades, such as a 26-year drought from 1539-1564 A.D. More recently, major droughts affected the region in the 1860s, late 1880s to mid-1890s, the 1930s, mid-1950s, and mid-1970s. The Dust Bowl of the 1930s stands out as a severe environmental disaster that devastated the Great Plains, primarily impacting western Kansas, Oklahoma, Texas, and parts of Colorado and New Mexico.
This period, from 1930 to 1940, was marked by intense drought, relentless winds, and massive dust storms, often referred to as “black blizzards.” These storms could reduce visibility to near zero and carry dust as far east as the Atlantic Ocean. The drought’s direct effects were primarily agricultural, with widespread crop failures due to insufficient rainfall, high temperatures, and strong winds.
The severity of the Dust Bowl was exacerbated by poor agricultural practices prevalent before the drought, including extensive plowing of natural grasslands for wheat cultivation and overgrazing. This stripped the soil of its protective cover, leaving the topsoil vulnerable to erosion by the region’s strong winds. The 1930s drought comprised multiple distinct drought episodes that prevented affected regions from recovering adequately.
Why Droughts Occur
Droughts in the Great Plains are influenced by natural climate variability and long-term climate change. Naturally occurring atmospheric patterns, such as shifts in pressure systems, can lead to reduced precipitation. One significant natural factor is the La Niña phenomenon, part of the El Niño-Southern Oscillation (ENSO) cycle, which brings drier and warmer conditions to the southern Great Plains.
Climate change also contributes, with rising global temperatures increasing evaporation rates from land surfaces and water bodies. This enhanced evaporative demand can worsen drought conditions even without a significant decrease in precipitation, as more moisture is drawn from the soil and plants. Changes in atmospheric circulation patterns due to warming can also alter the frequency and intensity of precipitation events, leading to longer dry spells.
Human land use practices have historically exacerbated drought conditions. During the 20th century, much natural grassland was converted to irrigated farmland, increasing erosion and intensifying drought impacts. Dry soil itself can enhance drought through a feedback loop, leading to warmer surface temperatures and further drying the soil and vegetation.
Consequences of Drought
The impacts of drought in the Great Plains are extensive, affecting agriculture, water resources, the economy, and ecosystems. Agriculture, a dominant land use, is particularly vulnerable to water deficits. Drought leads to widespread crop failures due to insufficient moisture, significantly reducing yields for staple crops like wheat. Livestock also suffer from reduced forage availability and stress from heat and water scarcity, leading to decreased productivity and potentially requiring culling of herds.
Water resources face significant depletion during drought periods. Aquifers, which supply much irrigation water for agriculture, can experience significant drops in water levels, increasing pumping costs and potentially making some wells unusable. River flows are also reduced, impacting municipal water supplies, hydropower generation, and navigation. The interconnectedness of these water systems means impacts in one area can cascade to others across the region.
Economically, drought imposes substantial losses on farmers and related industries. Crop failures and livestock losses directly reduce farm income, sometimes leading to bankruptcies. This affects businesses that rely on agricultural output, such as processing plants, equipment suppliers, and transportation services. The broader regional economy can experience downturns due to decreased spending and increased unemployment in agricultural sectors.
Ecosystems within the Great Plains also suffer. Soil degradation, including increased wind erosion and loss of topsoil, becomes more pronounced during dry periods when protective vegetation is sparse. Wildlife habitats are diminished, impacting species that depend on specific plant communities and water sources. Dry conditions increase the risk and severity of wildfires, which can devastate rangelands, forests, and agricultural areas, posing threats to human lives and infrastructure.
Managing Drought Impacts
Addressing drought impacts in the Great Plains involves a variety of strategies focused on water conservation, agricultural adaptation, and land management. Water conservation practices are important, including the adoption of efficient irrigation technologies such as drip irrigation and precision application systems, which deliver water directly to plant roots and minimize waste. Water reuse and recycling initiatives can also extend existing water supplies for various uses.
Agricultural resilience is enhanced through the development and adoption of drought-resistant crop varieties that can withstand prolonged periods of low moisture. Farmers can also implement adaptive planting strategies, adjusting planting times or crop choices based on seasonal precipitation forecasts. Diversifying agricultural practices, such as integrating livestock grazing with crop production, can improve overall farm resilience.
Land management techniques play a significant role in mitigating drought effects. Practices like no-till farming help retain soil moisture by minimizing soil disturbance, reducing evaporation, and improving soil organic matter content. Contour plowing and terracing on sloped lands can prevent water runoff and soil erosion, allowing more precipitation to infiltrate the soil. Maintaining healthy rangelands through sustainable grazing practices helps preserve native grasses, which are more resilient to dry conditions and protect the soil surface.
Early warning systems provide valuable information for proactive drought management. These systems utilize meteorological data, satellite imagery, and soil moisture sensors to monitor drought conditions and predict their onset and severity. This allows farmers, water managers, and communities to make informed decisions, such as adjusting planting schedules, implementing water restrictions, or deploying emergency aid, thereby enhancing preparedness and reducing potential losses.